The authorities were also blocking attempts to mention The Times or the prime minister, Wen Jiabao, in posts on Sina Weibo, an extremely popular mini-blogging service in China that resembles Twitter.

The Foreign Ministry spokesman on duty in Beijing early Friday morning did not answer phone calls seeking comment.

China maintains the world’s most extensive and sophisticated system for Internet censorship, employing tens of thousands of people to monitor what is said, delete entries that contravene the country’s extensive and unpublished regulations and even write new entries that are favorable to the government.

Rebecca MacKinnon, a senior fellow specializing in Internet free expression and privacy issues at the New America Foundation, a nonpartisan group headquartered in Washington, said that the Chinese interruption of Internet access was typical of the response to information that offended leaders.

“We hope that full access is restored shortly, and we will ask the Chinese authorities to ensure that our readers in China can continue to enjoy New York Times journalism,” she said in a statement, adding, “We will continue to report and translate stories applying the same journalistic standards that are upheld across The New York Times.”

Former President Jiang Zemin of China ordered an end to blocking of The New York Times Web site after meeting with journalists from The Times in August 2001. The company’s Web sites, like those of most other foreign media organizations, have remained mostly free of blocking since then, with occasional, temporary exceptions.

By 7 a.m. Friday in China, access to both the English- and Chinese-language Web sites of The Times was blocked from all 31 cities in mainland China tested. The Times had posted the article in English at 4:34 p.m. on Thursday in New York (4:34 a.m. Friday in Beijing), and finished posting the article in Chinese three hours later after the translation of final edits to the English-language version.

Publication of the article about Mr. Wen and his family comes at a delicate time in Chinese politics, during a year in which factional rivalries and the personal lives of Chinese leaders have come into public view to a rare extent and drawn unprecedented international interest.

The Times’s statement called China “an increasingly open society, with increasingly sophisticated media,” adding, “The response to our site suggests that The Times can play an important role in the government’s efforts to raise the quality of journalism available to the Chinese people.”

The New York Times is not the first international organization to run into trouble with Chinese censors. Google decided to move its servers for the Chinese market in January 2010, to Hong Kong, a semiautonomous Chinese territory outside the country’s censorship firewalls, after the company was unable to reach an agreement with the Chinese authorities to allow unrestricted searches of the Internet.

Bloomberg published an article on June 29 describing wealth accumulated by the family of Vice President Xi Jinping, who is expected to become the country’s next top leader as general secretary of the Communist Party during the coming Party Congress.

Since then, Bloomberg’s operations have encountered a series of problems in mainland China, including the blocking of its Web site, which is in English.

A version of this article appears in print on October 26, 2012, on page A12 of the New York edition with the headline: China Blocks Web Access To Times After Article. Order Reprints|Today's Paper|Subscribe